优化新增条码文本默认值提示

STS/Form2.Designer.cs

@@ -57,16 +57,15 @@
             // 
             // barcode_tb
             // 
-                this.barcode_tb.ForeColor = System.Drawing.SystemColors.GrayText;
+            this.barcode_tb.ForeColor = System.Drawing.SystemColors.GrayText;
             this.barcode_tb.Location = new System.Drawing.Point(124, 46);
             this.barcode_tb.Name = "barcode_tb";
             this.barcode_tb.Size = new System.Drawing.Size(234, 25);
             this.barcode_tb.TabIndex = 0;
             this.barcode_tb.Text = "T*****";
-            this.barcode_tb.Click += new System.EventHandler(this.barcode_tb_Click);
-            this.barcode_tb.HideSelectionChanged += new System.EventHandler(this.barcode_tb_HideSelectionChanged);
-            this.barcode_tb.TextChanged += new System.EventHandler(this.barcode_tb_TextChanged);
-            this.barcode_tb.MouseLeave += new System.EventHandler(this.barcode_tb_MouseLeave);
+            this.barcode_tb.GotFocus += new System.EventHandler(this.barcode_tb_GotFocus);
+            this.barcode_tb.LostFocus += new System.EventHandler(this.barcode_tb_LostFocus);
+
             // 
             // STI_tb
             // 

STS/Form2.cs

@@ -93,30 +93,24 @@ namespace STS
         {
             Form2Closed?.Invoke(this, EventArgs.Empty);
         }
-
-        private void barcode_tb_Click(object sender, EventArgs e)
+        //获得焦点
+        private void barcode_tb_GotFocus(object sender, EventArgs e)
         {
-            //如果是首次点击才执行以下代码
+            //点击时如果文本框里是默认值才执行以下代码
             if (barcode_tb.Text.Equals("T*****"))
             {
                 barcode_tb.Text = "";
                 barcode_tb.ForeColor = Color.Black;
             }
         }
-
-        private void barcode_tb_TextChanged(object sender, EventArgs e)
-        {
-
-        }
-
-        private void barcode_tb_MouseLeave(object sender, EventArgs e)
-        {
-
-        }
-
-        private void barcode_tb_HideSelectionChanged(object sender, EventArgs e)
+        //失去焦点
+        private void barcode_tb_LostFocus(object sender, EventArgs e)
         {
-
+            if (barcode_tb.Text.Equals(""))
+            {
+                barcode_tb.Text = "T*****";
+                barcode_tb.ForeColor = Color.Gray;
+            }
         }
     }
 }